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Alignment/Measuring

Hello all,

I'm back with another rapid-fire set of questions:

I'm having a lot of troubles getting my alignments down. So, basically where i work, we make exhaust tubes. I am almost always supplied a cad, with a predetermined origin and rotation orientation for my coordinate system. Because of this, I was told in the PC-Dmis 101 class, I would have to almost exclusively use best-fit alignments. Now, to do my alignment, I typically take four separate hits (using my mouse on my CAD) on each end of the tube in a kind-of plus pattern. Then i start a new alignment, click best fit, select all 8 of my hits, click compute, then ok, ok. So that's my initial alignment. Then I select auto-trigger mode and place 4 hits on either end of the tube (The cut part of the tube, by the way; what will eventually be measured as a plane soon), and create a second best fit alignment using the 8 new auto trigger hits.

After this is done, i shift-left click all my features starting at one plane, then all the cylinders down the part, then the last plane. I construct a pierce point between the first plane and first cylinder, and then the second plane and the last cylinder.

Here's where i get into trouble:

By blueprints typically call out distances between these two points across the X, Y, and Z axis, all separately. X normally goes down the length of the part, Y for the width, and Z for height. My X measurement is 'almost' always in spec, and then my Y and Z measurement is be off, sometimes significantly. This leads me to believe that there is a rotational issue present, likely due to how i built my first alignment. On occasion, my x measurement will be near perfect, then Y and Z be off my 8-10mm. Yet when i check the part to the check fixture the issue isn't present, which only further confirms that i am doing something blatantly wrong. In the PC-Dmis class, we only used the training block, so it was incredibly easy (relatively) to visualize my alignments, and make sure i had all degrees of travel and rotation locked.

Please, someone help me understand what I'm doing wrong, and what i can do to fix this issue. I have been doing this for around 6 months, (did the PC-Dmis 101 course this last December) so I don't know all the lingo or shorthand names for some of these actions i see some people talk about. Please explain how i should be doing it, as step-by-step as you can as though you were instructing an infant, because I'm definitely missing something here.

With my last post after the guy helping me realized I'm an incompetent newb at this, and he broke down what i needed to do step-by-step, it almost completely solved my issue that i was having.

Thank you.
Parents
  • The above is my code for a trial part I'm working on. The part i was working on is clearly flawed, so don't judge the measurements too harshly. However, even though the measurements are clearly off, I would have assumed the features I actually measured would have snapped a little more accurately to my CAD. And tbh, this part snapped better than most have in the past for me.

    If anyone notices any glaring issues with how this program is written, please jump in. I've gone through the first PCDMIS course for romer arms, and they barely touched on doing best fit/iterative alignments, so I'm not even 100% sure I'm doing even that part right. They told me those alignments would be covered more in-depth in the second class, which i was not scheduled to attend.

    I've only been doing this for about 8 months, so i don't know all the PCDMIS lingo, so you may have to 'color your responses in crayon' so to speak.
  • the first code tag should not have a backslash at the front. Also, your comment will need separate start/end code tags.

    Also, to make it more clear what you are doing, toggle SHOWALLINPUTS to ON in your alignment. Hold the mouse over it until it turns into a box, then click and change to on. Then share that alignment code.
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